JP2008221352A - Polishing method and polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing method and a polishing device capable of extremely smoothly polishing without leaving a sub surface damage on surfaces to be polished to form the surfaces to be polished free from chipping, and accurately polishing even a curved surface. <P>SOLUTION: An object to be polished (diamond cutting tool 20) is held by a cutting tool holding mechanism having adjustable angle and swing. The flank 20a and the face 20b of the diamond cutting tool 20 are polished by a plate-like polishing surface plate 10 having a deformable polishing surface. The polishing surface plate 10 is formed of a circular quartz plate having a thickness of 1 mm or shorter and a diameter of 20-40 mm. The surfaces to be polished (the flank 20a and the face 20b) are radiated with an ultraviolet L from an ultraviolet light source lamp 11. The rotational speed, position, and swing angle of the polishing surface plate 10 are adjusted by an automatic spindle swing mechanism. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polishing method and a polishing apparatus suitable for polishing a high-hardness polishing object such as a diamond single crystal and a diamond machined product.

Conventionally, in order to polish a diamond cutting tool or the like, as shown in FIG. 5, diamond particles (abrasive grains) 101 are dispersed on a rotating cast iron surface plate 100, and the polished surface (flank 102 a, A method (skyf polishing) using a mechanical action in which the scooping surface 102b) is pressed and polished is employed.
JP 2006-224252 A

  However, in the polishing method using such a mechanical action, fine scratches are generated, and residual strain remains under the processed surface, so that chipping on the order of several tens of nanometers occurs at the edge of the single crystal diamond tool. Even if the chipping is apparently small, microchipping and wear are likely to occur during ultra-precision cutting with this tool due to the effect of residual strain, and a highly accurate cutting surface can be obtained with good reproducibility. There is a problem that the tool cannot be used for a long life. In addition, it is known that the (111) plane of a diamond single crystal cannot be polished by conventional mechanical Skyf polishing. For this reason, there is a problem that a special cutting tool in which the (111) surface which is hard to wear is formed into a surface which is easy to wear can not be made.

  In the conventional polishing method, when the flank face of a diamond tool is polished by a cast iron surface plate, the flank surface has a semicircular curved surface. Polishing while slowly tilting around ± 60 degrees.

  However, with such a polishing method, it is difficult to stabilize the holding posture of the cutting tool, and the rotation of the surface plate surface causes micron-order vertical deflection, resulting in an error in the tip shape of the cutting tool. As described above, the conventional polishing method has a problem that it is extremely difficult and extremely expensive to polish a cutting tool having a small radius of curvature at the tip to a highly accurate shape with good reproducibility.

  For this reason, there has been a demand for a technique that prevents the generation of fine scratches and realizes high-precision polishing that is free of chipping and has no residual strain. In addition, Patent Document 1 discloses a technique for performing polishing by irradiating ultraviolet light in the same manner as in the present invention. In this technique, a polishing agent having a photocatalytic action is supplied to a surface to be polished. In addition, since the polishing surface plate is thick, it is difficult to process a portion having a curved surface such as a tip portion of a cutting tool.

  The present invention has been made in view of such problems, and the object thereof is to perform extremely smooth polishing without leaving subsurface damage on the surface to be polished, and to suppress the occurrence of chipping on the surface to be polished. At the same time, it is an object to provide a polishing method and a polishing apparatus capable of highly accurate polishing even for a curved surface shape.

  In the polishing method of the present invention, a plate-shaped polishing surface plate whose polishing surface can be bent by contact pressure with the object to be polished is brought into contact with the surface to be polished and rotated within the surface, and the object to be polished is The polishing target is polished by moving the polishing surface plate along the shape of the surface to be polished while irradiating the polishing surface with ultraviolet light.

  The polishing surface plate is preferably made of a softer material than the object to be polished. For example, when the object to be polished is a tool made of diamond, the polishing surface plate has a circular shape with a thickness of 1 mm or less and a diameter of 20 mm to 40 mm. Of quartz plate. The ultraviolet light has a wavelength of 170 nm or more and 400 nm or less, but preferably has a wavelength having energy equal to or higher than the band gap energy of the object to be polished or a wavelength having the same wavelength region as the light absorption band of the object to be polished. When the object is a diamond tool, it is an ultraviolet light having a wavelength of around 220 nm corresponding to the band gap energy (5.4 eV).

  Further, in the polishing method of the present invention, the difference between the desired shape to be polished and the current shape being polished can be monitored, and the degree of polishing by the polishing surface plate can be made larger at the part where the difference is large than at the part where the difference is small. desirable. Specifically, the stagnation time of the polishing platen may be lengthened or the rotation speed of the polishing platen may be increased at a portion where the difference is large.

  The polishing apparatus of the present invention supports a holding mechanism for holding a polishing target, a plate-shaped polishing surface plate whose polishing surface can be bent by a contact pressure with the polishing target, and a polishing surface plate that is rotatably supported within the polishing surface. A polishing surface plate driving means having a rotating shaft and capable of relatively displacing the polishing surface plate in accordance with the surface to be polished, and an ultraviolet light irradiation means for irradiating the surface to be polished with ultraviolet light. It is provided.

  In the polishing method and the polishing apparatus of the present invention, the surface to be polished is irradiated with ultraviolet light, and the polishing surface plate rotates and contacts the surface to be polished to follow the shape of the surface to be polished. Move and polish. At this time, the surface to be polished is activated by irradiation with ultraviolet light to form an oxide film, and this oxide film is removed by mutual friction with the polishing surface plate, whereby polishing proceeds. In particular, when the surface to be polished is a curved surface, polishing is performed in a surface contact state with a predetermined width while the polishing surface plate bends accordingly.

  In the polishing apparatus of the present invention, the polishing platen driving means has a function of turning the polishing platen and a function of changing the rotation speed of the polishing platen according to the polishing part, and the holding mechanism is polished. It is desirable to have a function capable of adjusting the posture angle of the target.

  According to the polishing method or the polishing apparatus of the present invention, the polishing surface plate is formed into a plate shape whose polishing surface can be bent by the contact pressure with the object to be polished, and the polishing surface plate is brought into contact with the surface to be polished. At the same time, the surface to be polished is rotated and the surface to be polished is irradiated with ultraviolet light so that it is polished smoothly without leaving any subsurface damage, and chipping occurs on the surface to be polished. In addition, it is possible to perform high-precision polishing even for a curved surface shape such as a flank of a diamond tool.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a main configuration of a polishing apparatus 1 used in the polishing method according to the first embodiment of the present invention. The polishing apparatus 1 includes a polishing surface plate 10 and an ultraviolet light source lamp 11, and performs polishing on a surface to be polished, for example, a surface to be polished (flank 20a and scooping surface 20b) of a diamond cutting tool 20.

The polishing surface plate 10 is softer than the diamond bit 20 and its polishing surface can be deformed by its contact pressure. In particular, when the curved surface portion (flank 20a) of the diamond bit 20 is polished, the curved surface portion has a predetermined surface. It is flexible enough to make surface contact with the width, and is specifically composed of, for example, a quartz plate (SiO ₂ ). This quartz plate has a flexural rigidity of, for example, about 0.01 MPa / mm to 1 MPa / mm, and is, for example, a disk shape having a diameter of 20 to 40 mm, preferably 1 mm or less, more preferably 0.5 mm or less. Having a thickness of

  By having such thickness and size, in this embodiment, the polishing surface plate 10 exhibits flexibility, and particularly, the curved surface (flank 20a) of the diamond tool 20 is polished with an appropriate contact pressure with high accuracy. It becomes possible to do. Moreover, since this polishing surface plate 10 is comprised by the quartz plate, it has transparency with respect to the ultraviolet light L, and can permeate | transmit the ultraviolet-ray from a back surface. The polishing surface plate 10 can be rotated in the plane by a spindle 12 attached to the center position thereof. As the spindle 12, for example, a spindle having a maximum performance of 50,000 rpm for a light load can be used. Further, the spindle 12 is attached to a spindle automatic turning mechanism 13 as shown in FIG. 2, so that the polishing surface plate 10 can be turned and the rotation speed can be adjusted according to the turning angle. Yes.

  The ultraviolet light source lamp 11 is disposed in the vicinity of the polishing surface plate 10 and the diamond cutting tool 20, and irradiates the polished surface (flank 20 a and scooping surface 20 b) of the diamond cutting tool 20 with ultraviolet light L. is there. The ultraviolet light L has, for example, a wavelength of 170 nm or more and 400 nm or less, and preferably has a wavelength of around 220 nm corresponding to the band gap energy (5.4 eV) of dyanmond. It is desirable to adjust the position of the ultraviolet light source lamp 11, the angle of the emitted ultraviolet light L, and the luminous flux so that the ultraviolet light L is irradiated to the entire surface of the diamond bit 20 to be polished.

  The arrangement of the ultraviolet light source lamp 11 may be on the back surface side of the polishing surface plate 10, and the irradiation of the ultraviolet light L is not limited to the lamp and may be a laser. When a laser is used, ultraviolet light can be directly applied to the surface to be polished of the diamond tool 20 from the back surface side of the polishing surface plate 10.

  As shown in FIG. 2, the diamond cutting tool 20 is held by a cutting tool holding mechanism 21, and the angle and the angle of the surface to be polished can be adjusted. As the bite holding mechanism 21, for example, a mechanism for brilliant cutting of diamond jewels can be used.

  In the polishing apparatus 1 according to the present embodiment, the ultraviolet light source lamp 11 has the polishing surface of the polishing surface plate 10 pressed against the surface to be polished (flank 20a, scooping surface 20b) of the diamond tool 20 with a predetermined pressure. Polishing is performed while irradiating with ultraviolet light L. Here, the position and angle of the polished surface of the diamond tool 20 are adjusted by the tool holding mechanism 21, while the rotation speed, position and turning angle of the polishing surface plate 10 are relatively adjusted by the spindle automatic turning mechanism 13, respectively. Thus, the flank 20a and the scooping surface 20b are polished with high accuracy.

  In the present embodiment, the diamond cutting tool 20 is firmly fixed to the correct position and posture by the cutting tool holding mechanism 21, so that the spindle 11 is attached to the tip of the diamond cutting tool 20 in a state where the polishing surface plate 10 is bent. By moving along the curved surface, the curved surface can be polished with high accuracy.

In the present embodiment, the diamond bit 20 is irradiated with ultraviolet light having a wavelength corresponding to the band gap energy, so that diamond is excited and chemically activated on the surface to be polished. That is, on the surface to be polished, hydroxyl radicals and oxygen radicals are generated by electron-hole pairs to form an oxide film. This oxide film is removed as carbon monoxide (CO) or carbon dioxide (CO ₂ ) by applying friction energy to the polishing surface plate 10, and polishing proceeds. By such polishing, the surface roughness of the polished surface of the diamond bit 20 becomes 0.3 nm or less in Ra, and there is no scratch and no residual distortion.

  Here, at the position where the curved surface (flank 20a) of the diamond tool 20 is polished, the contact portion between the curved surface and the polishing surface plate 10 is a surface contact having a slight width, thereby maintaining the polishing accuracy. Therefore, in the present embodiment, the difference between the target curved surface shape of the diamond tool 20 and the current shape during polishing is detected, and the polishing surface plate 10 is stagnated for a long time at a portion where the difference is large, and the portion where the difference is small In contrast, it is desirable to perform polishing so as to gradually approach a desired shape by advancing the polishing more. It should be noted that the polishing may be advanced by relatively increasing the rotational speed of the polishing surface plate 10 at a portion where the difference is large. Further, when polishing the flat scooping surface 20b, the polishing surface plate 10 may be set parallel to the scooping surface 20b.

  As described above, in the polishing apparatus 1 according to the present embodiment, the object to be polished (diamond bit 20) is not only mechanically reacted but also chemically reacted by irradiation with ultraviolet rays, and the reaction product is produced from diamond. Since the polishing surface plate 10 made of soft quartz is removed by the frictional action, the surface to be polished is free from scratches and residual strain, and the edge portion of the diamond bit 20 is free from chipping and residual strain. The lifetime can be extended.

  Furthermore, since polishing was performed while irradiating with ultraviolet light, it became possible to polish the single crystal (111) plane, which was conventionally impossible to mechanically polish, in the same manner as other crystal planes. A new type of cutting tool having a diamond (111) surface set on a surface that is easily worn and deformed during cutting, such as the scooping surface 20b, can be manufactured, and ultra-precise and ultra-long-life cutting tools can be polished.

  Further, since the polishing surface plate 10 is made of quartz softer than diamond and the thickness of the quartz plate is made thin, the entire surface plate is flexible, and the diamond bit 20 is held by the bite. The mechanism 21 is firmly fixed in an accurate position and posture, the polishing surface plate 10 is brought into contact with the surface to be polished of the diamond tool 20, and the rotating shaft (spindle 11) is set to the tip of the diamond tool 20 in a state of bending. By moving along the curved surface, the curved surface can be accurately polished in a surface contact state with a predetermined width.

  Further, in the present embodiment, the polishing surface plate 10 is made of a thin quartz plate having a small diameter, so that the shape being polished can be polished while being observed microscopically. In addition, since the quartz plate is transparent to ultraviolet light, it is possible to irradiate the polishing surface plate 10 from the back surface, so that the surface to be polished of the diamond tool 20 is effectively irradiated with ultraviolet light. Can be polished.

  Next, a second embodiment of the present invention will be described with reference to FIG. The polishing apparatus 2 according to the present embodiment has a structure in which the polishing surface plate 10 made of the above-described quartz thin plate is held by a holding disk 31 made of, for example, aluminum. The holding disk 31 has a central convex portion 31A and a ring-shaped peripheral convex portion 31B on the surface side, and holds the polishing surface plate 10 made of a quartz thin plate by the central convex portion 31A and the peripheral convex portion 31B. ing. The holding is performed by an adhesive, for example. The spindle 12 is attached to the center of the back surface of the holding disk 31. Deflection of the polishing surface plate 10 that occurs during polishing is absorbed by the cavity portion 32 surrounded by the central convex portion 31 </ b> A and the peripheral convex portion 31 </ b> B and the polishing surface plate 10. The holding disk 31 is provided with a ring-shaped ultraviolet light transmission hole 33 facing the cavity portion 32, and the ultraviolet light from the ultraviolet light source lamp 12 passes through the ultraviolet light transmission hole 33 from the back side of the quartz thin plate, and the diamond bit 20. The tip is irradiated.

  In the present embodiment, since the polishing surface plate 10 made of a quartz thin plate is held by the holding disk 31 so as to be able to bend, there is no possibility that the quartz thin plate is cracked. Other functions and effects are the same as those of the above-described embodiment, and thus description thereof is omitted.

  In the embodiment described above, the diamond bit 20 is used as an object to be polished. However, the present invention is not limited to this, and may be a diamond single crystal, such as silicon carbide (SiC) or gallium arsenide. It can also be used for polishing (GaAs) or the like. Further, although a quartz plate is used as the polishing surface plate 10, other materials may be used as long as they are soft to the object to be polished and have flexibility as a whole.

1 is a perspective view illustrating a schematic configuration of a polishing apparatus according to a first embodiment of the present invention. FIG. 2 is a plan view of the polishing apparatus in FIG. 1. FIG. 2 is a side view of the polishing apparatus of FIG. 1. It is a sectional side view showing the polish device concerning a 2nd embodiment of the present invention. It is a perspective view for demonstrating the conventional grinding | polishing method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus, 10 ... Polishing surface plate, 11 ... Ultraviolet light source lamp, 12 ... Spindle, 13 ... Spindle automatic turning mechanism, 21 ... Bite holding mechanism, 20 ... Diamond bite, 20a ... Flank, 20b ... Scuffing surface, 31 ... holding disc

Claims (10)

A plate-like polishing surface plate whose polishing surface can be bent by contact pressure with the object to be polished is brought into contact with the surface to be polished of the object to be polished and rotated within the surface; and
A polishing method comprising polishing the polishing target by moving the polishing platen along the shape of the polishing target surface while irradiating the polishing target surface with ultraviolet light. . The polishing method according to claim 1, wherein the polishing platen is made of a softer material than the object to be polished. 3. The polishing method according to claim 1, wherein the polishing surface plate has a flexibility that allows surface contact with a predetermined width of the curved surface portion of the polishing target when the polishing target having a curved surface portion is polished. . The polishing method according to claim 1, wherein the object to be polished is a tool made of diamond. The ultraviolet light has a wavelength having an energy equal to or higher than a band gap energy of the object to be polished, or a wavelength having the same wavelength region as the light absorption band of the object to be polished. The polishing method according to item. The difference between the desired shape of the object to be polished and the current shape during polishing is monitored, and at a portion where the difference is large, the degree of polishing by the polishing platen is made larger than a portion where the difference is small. 6. The polishing method according to any one of 5 above. A holding mechanism for holding an object to be polished;
A plate-like polishing surface plate whose polishing surface can be bent by contact pressure with the object to be polished;
A polishing surface plate driving means having a rotating shaft that rotatably supports the polishing surface plate in a polishing surface, and capable of relatively displacing the polishing surface plate according to the surface to be polished;
A polishing apparatus comprising: ultraviolet light irradiation means for irradiating the surface to be polished with ultraviolet light. The polishing apparatus according to claim 7, wherein the polishing platen driving unit has a function of turning the polishing platen and changing a rotation speed of the polishing platen according to a polishing portion. . The polishing apparatus according to claim 7 or 8, wherein the holding mechanism has a function of adjusting a posture angle of the object to be polished. The polishing table according to any one of claims 7 to 9, wherein the polishing platen has a flexibility that allows surface contact with a predetermined width of the curved surface portion of the polishing target when the polishing target having a curved surface portion is polished. The polishing apparatus according to 1.

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